Piezoelectric actuator or motor, method therefor and method for fabrication thereof

ABSTRACT

This invention relates to an actuator or motor comprising an electromechanical material which alters its shape under the influence of an electrical voltage. Said actuator comprises at least a monolitic module ( 1,2 ) with electrodes integrated in said electromechanical material and in that the force or displacement due to the applied voltages is transferred, to the point to be actuated or moved by the shape change of the material, using at least two independent contact points. The invention also relates to a method for fabricating said actuator or motor.

TECHNICAL FIELD OF THE INVENTION

The invention relates to small motors and actuators comprisingelectro-mechanical materials which alters its shape under the influenceof an electric field. In particular the invention relates to motors andactuators in which the motion relative another body is created byrepetition of small steps. The invention also relates to a method ofdriving such motors and to a method for manufacturing the motors.

RELATED ART

There is a great need for high performance motors in the size rangebelow a few millimeters, motors of the kind which should be able tocreate linear and/or rotating motion. It is often desirable that thiskind of motors both have a high precision and can exert large forces.One may realize that since reliable and cheap motors of this kind isrequested for e.g. driving cameras, hard disks, CD-players etc thepotential market is huge. Also in the area of medical instrumentation,e.g. pumps, such motors are of great interest.

In the state of the art, various devices based on electromechanicalmaterials exist. Electromechanical materials have the interestingproperty of changing its shape when they are influenced by an electricfield. Pieces of electromechanical materials, fixed to a base plate willtherefore move their non fixed surfaces when electric fields are appliedto them. Such motions, contractions or expansions, may be used forconstructing different types of motors or actuators.

Techniques often used for motors in the size range one centimeter andabove are referred to as ultrasonic motor techiques. Other terms oftenused for the same kind of devices are resonance, vibration, travellingwave or impact motor devices. Typically, in such motors,electromechanical materials impose a resonance vibration into itself anda solid piece material, normally a metal block. In e.g. a travellingwave motor, protruding portions of the metal block are forced into anelliptical movement, and another object in contact with these protrudingportions is forced to move in accordance with these movements . Whengoing to miniature motors, this technique will be disadvantageous, sincethe movements become too small and limited by a non-controllable surfacetopography etc.

A more appropriate approach to miniature motors based onelectromechanical materials is to use devices which operate off theinherent resonance. One particular actuation principle which has a greatpotential to fulfil the demands for such motors is an Inchworm® type ofmotor (M. Bexell, A.-L. Tiensuu, J-A. Schweitz, J. Söderkvist, and S.Johansson, Sensors and Actuators A, 43 (1994) 322-329). The motion iscreated by repetition of small steps in a similar way to the insectinchworm, hence the name (The micropositioning book. Fishers, N.Y.:Burleigh Instruments, Inc. (1990)). This motion principle will in theremaining part of this appplication be referred to as a “non-resonancestep” technique, to be distinguished from the above described ultrasonictechniques. Portions of electromechanical material may also be referredto as PZT.

The principle for this motion is simple. A moving body is held betweentwo claws, one on each side of the moving body. Each claw consists of alongitudinal piece of PZT, substantially parallel to the moving body,and at each end a transversal PZT is present. The PZT:s are assembledonto metal bodies. Assuming all of the transversal PZT:s are energizedand expanded in the start position, gripping the moving body, the twoopposite front transversal PZT:s are recontracted, loosing the grip ofthe moving body. An electrical field is applied to the longitudinalPZT:s, expanding their lenghts, and the front transversal PZT:s aresubsequently forced to expand again, gripping the moving body at a newposition. The rear transversal PZT:s loose their grip of the moving bodyand the longitudinal PZT:s are allowed to contract again, whereafter therear PZT:s again grip the body. The result of such a cycle is that themoving body has moved relative to the two claws.

An electronic control device is needed for a controlled operation of theabove actuator. The electronics should supply the different PZT:s withappropriate voltages in an appropriate order. Since such a sequence ofvoltages can be repeated very fast, a relatively fast movement ispossible to obtain despite the small step size.

There are some crucial factors limiting the development of existingproducts based on the non-resonance step principle. Among the limitsthere is the difficulty of achieving a sufficient stroke of theindividual actuating elements and the need for a costly high precisionassembly of the elements and other parts in the system. Some solutionsto these problems have been presented in the Swedish Patent ApplicationNo. 9300305-1 by Johansson. Using actuating elements with at least atwo-axial motion capacity, the number of elements has been reduced. Atthe same time motion magnification by internal levers (e.g. bimorphs) inthe elements can be included which gives a large freedom in design.According to these ideas a miniature motor has been built and has provento present the desired high torque and motion capacity as predicted (M.Bexell and S. Johansson, Transducers, Stockholm, Sweden (1995)528-News).

By the above mentioned solution, a motion relative to another body maybe acheived in the following way. Four active elements ofelectromechanical material are mounted on a passive base plate, normallymade of silicon, and the moving body is held against the protrudingactive elements. All elements consist of two vertically dividedcontrolled portions of PZT, both extending between the base plate andthe moving body. By applying a voltage resulting in an electrical fieldin the horisontal direction to the first portion of the PZT but not tothe other portion, one part is tending to contract in the verticaldirection, while the other is unaltered. Since the two portions aremechanically integrated into one piece, the active element willsubsequently bend towards the side of the live portion. If both portionsare energized, the whole element will contract, and if only the secondPZT is imposed by a voltage, the element will bend in the otherdirection. By varying the voltage in the different portions, a contactpoint on the top of the active element can travel along any path withina rhombic area. A “contact point” is of course not a point in amathematical sense, but rather a small “contact area” depending on theactual geometries and normal forces, and these expressions are in thepresent description used in a synonomous manner.

By using four active elements arranged after each other, in thedirection of the sidewise movement, a moving action on the body can beacheived. By letting the first and third elements move in phase, andmoving the second and fourth elements out of phase, a non-resonance stepmotion similar to the above described, is acheived.

At present, this motor gives the highest torque per volume of allpresently known miniature motors. There are some disadvantages even withthis construction, which is the origin of the present invention. In theprevious patent application the motor, for instance, consisted of activeelements mounted on a substrate, and typically soldering has been usedas the assembling method. This is a fairly time consuming operation andtherefore costly. Most applications demand however that the price ofeach motor should be very low.

The above patent application, bimorph or multimorph elements were usedto obtain two-axial motion and at the same time possibility for strokemagnification. The disadvantage with a single clamped bimorph is thatthe force capacity is greatly reduced in comparison with an ideal lever,which is the reason why these types of elements normally are used forpositioning when there is no considerable need for forces. A doubleclamped bimorph, a curved membrane or an arch-shaped structure have abetter force capacity for a given stroke magnification, as disclosed inthe U.S. Pat. No. 5,589,725. However, no completely satisfying designfor these leverage structures has been presented yet. Either they aretoo expensive to produce (for instance assembling) or the performance isnot sufficient.

One important application for miniature motors is in catheter type ofinstruments (for medical use). The problem is how to control the shapeof a long narrow tube. Either the tube is the instrument itself or is anaid for other catheter type of instruments. There exist only a fewsuggestions or examples of how to control the motion of a tube typestructure of dimensions less than a diameter of 5 mm. All suggestionshave obvious disadvantages. Either the motion is too slow, the tube tooweak or results in too much heating.

Multilayered structures of piezoelectric materials conventially arefabricated in a following manner. A green tape is made by tape casting amixture of piezoelectric powder and a polymer binder. An electrodepattern is defined by screen printing a metal paste on to the greentape. The multilayer is made by laminating these tapes and subsequentlyheat treat the structure in two steps, first a polymer burn out andsecondly sintering, to create a monolithic unit. The outer shape is mostcommonly cut by a sharp wedge in the green state but other shapingtechniques, such as drilling, cutting and punching, could be used aswell. The contacts to the different electrode layers are madesubsequently to the sintering by printing or painting metal paste on thesides, orthogonally to the layers, and a subsequent heat treatment ofthe paste forms a metal.

In a major part of the future applications for miniature motors thefabrication has to be cheap. Present microfabrication techniques arerather expensive and yet far from suited for making cheap activecomponents. The main needs are electrode patterning and electricinterlayer connection in the electroactive material.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a motor or actuator,using the non-resonance step principle, which comprises as small anumber of separate elements as possible, maintaining or improving theprecision of the motion of the device. It is also an object of thepresent invention to provide manufacturing methods for such motors oractuators.

Another object of the present invention is to provide a motor oractuator which can be further miniaturised.

A further object of the present invention is to provide a motor oractuator, which can achieve a large range of combined motions.

The above objects are acheived by a motor or actuator according to claim1. An actuator or motor comprises electromechanical material providingthe moving action, whereby the motion is created by repeatedlyperforming small steps. The actuator comprises at least one monolithicmodule with electrodes integrated in the electromechanical material. Theterm “monolithic” will in this description stand for one single integralbody, finally integrated by a heat treatment, e.g. a sintered block ofdifferent materials. The actuator has at least two contact points with amoving body, contact points of which can be positioned independently ofeach other relative to a passive part in the monolithic module in atleast two independent directions. The module can by itself or incombinations with other modules be used for moving another body.

The manufacturing method according to the present invention is a methodfor creating complex electrode arrangements in a ceramic body, such asan electromechanical material, which method comprises replication of ageometrical shape into a polymer tape with grains of electromechanicalmaterial. This replication accomplishes the three dimensional patterningof the modules.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings, in which

FIG. 1 is a preferred embodiment of a hexagonal, monolithic structureaccording to the invention;

FIG. 2 illustrates an embodiment in the form of a tube, withcontrollable shape;

FIG. 3 is a variant of the embodiment according to FIG. 2 including aconcentric inner tube with a peristaltic internal motion;

FIG. 4 shows an embodiment allowing a combined rotating and linearmotion;

FIG. 5 shows an arch-shaped structure with an improved force capacityfor a given stroke magnification;

FIG. 6 illustrates a rolling process to define the shape of anelectroactive tape;

FIG. 7 shows some of the resulting geometries of a plastically deformedtape of electroactive material coated with an electrode layer;

FIG. 8 shows a further method of producing an actuator according to theinvention; and

FIG. 9 shows alignment geometries in films used as starting materials.

DETAILED DESCRIPTION OF EMBODIMENTS

A preferred embodiment of the invention is illustrated in FIG. 1, whichdiscloses a monolithic module integrating all the active elements. Themonolithic module can be described in terms of a larger hexagonalmechanically passive part 1 and active elements 2, which are integralparts of the module. Therefore none of the parts shown in FIG. 1 arepossible to dismount, since they together form the monolithic module.The active elements 2 are arranged to be in contact with, or at least inthe vicinity of the surface of the body which is supposed to be movedrelative to the module (not shown in the figure).

Each element 2 consists of an electromechanical material, preferablypiezoelectric, which typically is a multilayered structure. Anelectromechanical material responds to a certain electrical fieldapplied across it. In order to have a large shape change upon applyingthe voltage, the electrical field in each portion of the material has tobe high. For a non-layered material, a single voltage has to be appliedacross the whole structure, why the requested voltages have to be veryhigh. One of the advantages with a layered structure is that thenecessary voltages to achieve a particular electrical field becomeslower, which is desired for the matching of the structure with, e.g.,the drive electronics. This is accomplished by introducing electrode andearth layers within the material. Upon supplying a relatively lowvoltage to each electrode, the local electrical field can still be highenough for a large shape change.

A possible configuration of such a layered structure is shown in theupper part of FIG. 1, where an enlarged sketch of one of the elements isshown. Electrical contacts 17I-17VI are connected to electrodes 16I-16VIand a ground contact 17 O with ground layers 16 O in between theelectromechanical layers in the figure. The electromechanical layers inthe figure are drawn as a transparent volume for the sake of clarity,even though the electromechanical material in reality not beingtransparent. The whole piece shown in the enlarged picture, includingthe electrodes, contacting etc. are integral parts of the entiremonolithic module.

With the above described configuration of the active elements 2, eachactive element 2 can be forced to move in three independent directions.By applying the same voltage to all electrodes 17I-17VI, the entireactive element 2 elongates its height, i.e., the contact point againstthe body to be moved is moved upwards. By, for instance, applying avoltage to the electrodes 17I and 17II, the corresponding portion of theelectromechanical material will try to elongate in height, while theother portions are unchanged. In the Figure, this situation will resultin a tilting of the active element 2 inwards, thus moving the contactpoint inwards and somewhat upwards. Similarly, by applying a voltage tothe electrodes 17II-17IV, the active element 2 is forced to bend to theleft side in FIG. 1. By combining such movements, the contact point ofthe active element 2 can be forced to move in an arbitrary direction,within certain limits.

Thus, the use of electrode arrangements such as illustrated in FIG. 1allows the element top surface to move arbitrarily in space relative tothe substrate. If there are at least two independent sets of activeelement, arranged for instance as A and B in FIG. 1, then the module caneasily be used with an non-resonance step technique type of motor.

One example of such a motion is a rotational one. Assume a body to bemoved is placed on top of the active elements 2, having one contactpoint for each element 2 when not active. The stepping cycle starts withelongating the active elements of set A, whereby only the three contactpoints with A elements remain. Then the set A elements are activated insuch a way that they all are bent in parallel to the closest edge of thehexagonal passive part 1. The moving body will then rotate a small anglearound an axis going through the center of the module. The set Belements are put in contact with the moving body and the set A iscontracted and straightened. The cycle then continues by bending the Bset, and so on.

A linear motion may also be accomplished by instead bending the sets ofelements in a certain direction. It is easily understood that anyarbitrary motion within the plane of the active elements may be acheivedin this way.

In the above examples, the elements are assumed to be driven by constantvoltage pulses, but typically in reality all elements are driven withsinusoidal voltages to achieve an elliptical motion of the elementcontact point relative to the substrate. The two sets A and B are thentypically rotating about 180 degrees out of phase. For each elementthere are at least two phases and a simple arrangement in FIG. 1 wouldbe to drive electrodes I and VI with one sinusoidal wave and III and IVwith another. These should be phase shifted about 90 degrees to obtain asuitable elliptical motion of the contact point. There are of coursenumerous ways to arrange the electrodes in the active elements and toapply voltages to the contacts in order to achieve a motion according tothe non-resonance step technique.

The actual electronics may be constructed according to conventionalmethods and will not be further discussed in this application.

It is also desirable to integrate the control electronics generating thephase shifted voltages as well as various sensor (e.g. force andposition) feed-back and communication electronics into the integratedmodule or attached thereto. In such a way a specially tayloredelectromechanical actuator module may be available as onemonolithicpiece.

The actuator according to an embodiment of the present invention isadvantageously used for medical instruments of catheter type. Assumingthat control and communication electronics are integrated within (ormounted on) the module, an arrangement such as shown, e.g., in FIG. 2solves previous problems. The arrangement comprises a number of modulesaccording to the present invention, where the whole module 1 has a wedgeshape, typically with the back side 3 tilted. The wedge shape could beeither the module itself or a separate unit, free or mounted on themodule. It is also convenient to use an elastic material or an elasticstructure (e.g. spring type of geometry) in-between or as the wedgeshaped unit.

A number of different movement modes are easily obtainable by such anarrangement. If the modules are rotated relative to each other, atilting action of the total arrangement results.

This means that a rotational movement of one of the modules will conveythe above arranged modules along circular paths, the radius of which inrelation to the distance to the rotating module will correspond to thewedge angle. A clarifying example is the case where the arrangementabove the rotating module is linear. In such a case the upper part ofthe arrangement will follow the surface of a cone.

Two modules operating together can create rotation without tilting. Thisis obtained by arranging the two wedges in oposite directions, so thatthe wedge angles compensate each other. In such a way a rotationalmovement may be transferred further in the arrangement of FIG. 2.

One possible solution for assembly of such a system would be to enclosethe modules including the wedges into a bellow-shaped tube 4. The tubeis creating the normal force in-between the many modules. At the sametime it serves as a protective envelope and electrical connection.

All modules could be connected to a serial communication bus (e.g. 2-4electrical wires) to reduce the number of electrical connections betweenthe modules.

Another elegant catheter design is to use modules with a sphericalcontact surface, as illustrated in FIG. 3. The spherical contact surface5 makes it possible to rotate each module relative to the next withoutany tilting. It is also possible to tilt each individual module in anydirection if three-axial active elements are used. This corresponds tothe linear motion described in connection with FIG. 1. The catheter willbe more flexible in comparison to the previous design, FIG. 2. However,the wedge shaped design is much easier to manufacture, which might be anadvantage in some applications.

There is also a desire to transport for instance liquids in and outthrough the catheter working end. This could be achieved with a tube 6in the centre of the modules, FIG. 3. A peristaltic type of liquidtransport may be obtained if two tube constrictions 7, separated by acertain distance, are moving together. Constrictions can be made by tuberotation or stretching using the modules. By moving the individualmodules according to a certain scheme it is possible to move suchconstrictions along the arrangement, and if both constrictions are movedtogether, the volume enclosed in-between, will be brought through thecenter of the arrangement.

Among the high performance applications are, e.g., linear motion infast, high precision equipment. One such design is shown in FIG. 4. Itconsists of three modules assembled into a stator structure 8. Thestator structure has a geometry that creates a radial force against therotor 10 by spring type elements 9. If the active elements in the moduleare made for three-axial motion as indicated in the figure, then bothaxial motion and rotation of the rotor can be achieved. As seen in theenlarged module, the four active elements are divided into two sets.This is also done for the two other modules of the motor. These two setsof active elements forms gripping claws in analogy with thenon-resonance step principle motion, in analogy with the description ofFIG. 1. If the active elements in each set are bent in a tangentialdirection during operation, the resulting motion of the rotor will be arotation. If the active elements in each set are bent in an axialdirection during operation, the resulting motion of the rotor will be aaxial translation. Of course, these two motion modes may be combinedsimultaneously, by letting the active elements in the modules bend in adirection between the two pure motion cases.

A simple rotating motor can be constructed in an analogous way using twospring loaded structures similar to those of FIG. 1 with a rotor in themiddle. In the simplest version the contact points ot two monolithicmodules are pressed with a clamping spring structure against either sideof a planar rotor disc. If a hole is, e.g., drilled through themonolithic module, the rotor shaft connected to the rotor disc could goorthogonally to the module in the centre.

A body to be moved by the module is actually moved by a friction type offorce. To acheive such a force, some kind of normal force towards themodule is necessary. The normal force necessary to create motion inbetween the stator and rotor, i.e between a module and the body to bemoved in relation to the module, can be acheived in many ways. All typesof forces can be used: gravitation, magnetic, electrostatic, molecular,atomic, viscous forces. The elastic forces in springs are of courseattractive for many applications but the use of permanent magnets mightbe one of the most cost-efficient methods. By elastic springs areunderstood all mechanical arrangements which presses the moving bodyagainst the modules. These “springs” normally constitute the surroundingencompassing material. They may, however, reqiure some amount ofmounting effort, which may make such solutions less cost efficient.

The motion range of each active element in the modules is an extremelyimportant parameter. A large enough motion range in relation to thefabrication precision and accuracy is needed. While the elementconstruction given in FIG. 1 might be sufficient for certain motorsizes, some stroke magnification mechanism must be used when the motoris further miniaturised.

In devices according to the state of the art some stroke magnificationefforts are done, however, quite insufficient. The leverage structure 11schematically presented in FIG. 5 solves all these problems. It is amonolithic body consisting of arch-shaped structures arranged with twooppositely oriented arches 12 as a base unit. The arches are typicallyof electroactive material with layers of electrodes and connected insuch a way that, for a given applied voltage, one arch increases itscurvature and the other arch decreases its curvature. In that way theentire body will expand in the vertical direction and horizontal forces14 will be compensated for. The horizontal forces are, e.g., due tohorizontal shape changes to accomplish the change of curvature. Sinceone arch decreases its curvature and the other increases its curvature,the resulting forces will have opposite signs in the horizontaldirection, and hence are compensated within each base unit. Byintelligent distribution of the electrodes in the module three axialmotion is acheived. For instance, the electrode areas in each arch couldbe divided in analogy with the active elements 2 in the monolithicmodule 1 and hence the central portion which is used for the transfer offorce and displacement will be possible to move also in a horizontaldirection. The volume in between the arches is either empty or filledwith suitable elastic material. An elastic material such as a rubberwill serve e.g. as a protection against overloading without asubstantial loss of actuator performance.

According to the present invention a method of fabrication of monolithicmodules is disclosed. In this method there is of course a desire todirectly form the monolithic module to its final shape, includinginternal voids or similar. In FIGS. 6-9, some possible processingtechniques to solve these problems are described. In FIG. 6 rollers 18with geometrical shapes 19 are used for replication of these shapes intoa tape of electro-mechanical material 15. An alternative to rollers isthe use of the somewhat slower stamping process, which has the advantageof a cheaper tool fabrication. The shapes fabricated by the replicationprocess are principally used for definition of electrode layers andconnections between layers in the green state, i.e., before heattreatment. Other uses of the replication technique is as an aid foralignment, and to define void volumes, which is further described below.

Depending on the actual application, the tape may be covered withelectrode layers 16 as shown in FIG. 7, prior to the above describedreplication. If the tape is covered with electrode layers 16, either onone or on both sides, the patterning of the electrodes can then be madedirectly by the rolling process, FIG. 7. The electrode layer is dividedby plastic deformation of the tape resulting in separate electrodeareas, as can be seen in FIG. 1. The electrode patterning on top of,e.g., a polymer tape with piezoelectric grains is normally difficult bymeans of standard litographic techniques according to the state of theart, and the method according to the present invention solves thisproblem in an elegant way.

Electrical connection between the layers can also be made by formingholes 20 by plastic deformation of the tape. In FIG. 7, the walls of thehole 20 are still covered with electrode material and an electricconnection is formed between the two layers. Alternatively, a holeformed in the above described way may be filled with electricallyconducting paste. In this way electrical connections may be produced notonly horizontally, but also vertically through the modules. Anothermethod for formation of electrical connections would be to use rolling,see FIG. 8, folding, twisting etc. in combination with plasticdeformation to achieve the desired electrical connection. In themanufacture of actuators based on electromechanical materials, one ofthe time consuming and overall limiting processing steps is theelectrical connection between the layers. Simple folding, where twodifferent parallel layers are connected in the fold itself, solves thisproblem in certain applications since there will be no need forconnections inbetween the layers. Rolling and twisting of the polymertape with electroactive material are other methods for formation ofelectrical connections inbetween different layers without forming holes.

Subsequent processing steps are to laminate these layers and by heattreatment produce a monolithic unit or module, methods known per se.These steps are therefore not further discussed in this disclosure.Internal void volumes (or suitable materials) could be made by includinglayers with non-electroactive material. Such layers may be introducedbefore or after the replication step as well as during the laminatingstep. By the replication, polymer volumes of different geometries arecreated. During heat-treatment, in particular the conventionalintroductional burnout heat treament, a polymer material woulddisappear, for instance. A void volume is thus possible to create byintroducing a patterned polymer layer with aid of the replicationtechnique.

External friction layers, suitable at the top of the active elements ofthe module, etc. could be included in the same manner. Since the outerparts of the active elements are the portions of the modules which arein mechanical contact with the moving body, these are the only parts ofthe modules, which are exposed to tribological effects. However, sincethe moving action is dependent on a certain friction, there has to besome sort of contact. One way to improve the resistance to wear etc.could then be to cover the outermost parts of the active elements withexternal friction layers. Such layers are also easily introduced in thefabrication method according to the present invention, by adding one orseveral layers of wear resistant material on top of the finalelectromechanical layers. The friction layers are subsequentlyintegrated into the module during the sintering process.

One difficult step in the manufacturing process is the alignment of thedifferent lamination layers prior to the heat treatments. Since theallover accuracy has to be in the order of μm, a corresponding accuracyhas to be obtained during the alignment process. Alignment duringlamination can be greatly simplified if particular alignment geometries21, e.g. peg in hole, also are replicated in the film. From FIG. 9, itis seen that geometrical structures can assist in the alignmentprocedure. In FIG. 9, certain geometrical edges on three layers inseries are denoted by 21A-21F. Protruding edges, 21A, 21B and 21E,correspond to recess edges, 21C, 21D and 21F, respectively, in theunderlying layer. When positioning such layers on top of each other,these edges will fit together and guide the layers to be accuratelyaligned.

Although certain preferred embodiments of the invention have beenpresented in the above description, it should be noted that theinvention is not limited thereto. It is understood that variations andmodifications according to the spirit of the invention should beincluded and the invention is solely defined by the scope of theappended claims.

What is claimed is:
 1. An actuator or motor having electromechanicalmaterial which alters its shape under the influence of an electricfield, whereby motion relative a body is created by non-resonantrepetition of small steps, said actuator or motor comprising at leastone monolithic module with electrodes integrated in saidelectromechanical material, said monolithic module being a sinteredblock and having at least one passive part and at least two activeelements, one independent contact point at each active element beingprovided against said body, which contact points are positionableindependently of each other in at least two independent directionsrelative to said passive part of said monolithic module, whereby saidmonolithic module by itself or in combination with others is used forcreating said motion.
 2. An actuator or motor according to claim 1,wherein said contact points are positionable independently of eachother, relative to said passive part of the monolithic module, in threeindependent directions.
 3. An actuator or motor according to claim 1,wherein said contact points of the monolithic modules are located in aplane being inclined relative to a base plane of said monolithic moduleor an attached unit.
 4. An actuator or motor according to claim 1 ,wherein said monolithic modules have a spherical contact geometry.
 5. Anactuator or motor according to claim 3, further including a bellowshaped tube, structured and arranged to create a normal force betweensaid monolithic modules.
 6. An actuator or motor according to claim 1,wherein said monolithic modules are pressed against said body.
 7. Anactuator or motor according to claim 6, wherein said monolithic modulesare pressed against said body by gravitational, electrostatic,molecular, atomic or viscous forces.
 8. An actuator or motor accordingto claim 6, wherein said monolithic modules are pressed against saidbody by magnetic forces.
 9. An actuator or motor according to claim 6,wherein said monolithic modules are pressed against said body by elasticspring forces.
 10. An actuator or motor according to claim 1, whereinthree dimensional cavities are integrated in said monolithic modules.11. An actuator or motor according to claim 10, wherein at least a partof said active elements is built-up by base units, comprisingstructures, which are curved in two or in three dimensions.
 12. Anactuator or motor according to claim 10, wherein at least a part of saidactive elements is built-up by arch-shaped structures which are fixed toeach other at at least two ends.
 13. An actuator or motor according toclaim 11, wherein said base units are curved membranes or platestructures.
 14. An actuator or motor according to claim 10, wherein saidcavities are filled with rubber-like material.
 15. An actuator or motoraccording to claim 1, wherein said monolithic module also comprisescontrol electronics generating phase shifted voltages and variousfeed-back and communication electronics of a sensor, said sensormeasuring at least one characteristic such as force and position.
 16. Anactuator or motor arrangement having an actuator or motor havingelectromechanical material which alters its shape under the influence ofan electric field, and a body, whereby motion relative said body iscreated by non-resonant repetition of small steps, said actuator ormotor comprising at least one monolithic module with electrodesintegrated in said electromechanical material, said monolithic modulebeing a sintered block and having at least one passive part and at leasttwo active elements, one independent contact point at each activeelement being against said body, which contact points are positionableindependently of each other in at least two independent directionsrelative to said passive part of said monolithic module, whereby saidmonolithic module by itself or in combination with others is used forcreating said motion, and in that said body has a wedge shape.
 17. Anactuator or motor according to claim 16, wherein said body comprises anelastic material.
 18. An actuator or motor according to claim 16,wherein said body is an elastic structure.
 19. An actuator system havinga number of modules comprising electromechanical material which altersits shape under the influence of an electric field, whereby motionrelative a body is created by non-resonant repetition of small steps,said modules being monolithic modules with electrodes integrated in saidelectromechanical material, each of said monolithic modules being asintered block and having at least one passive part and at least twoactive elements, one independent contact point at each active elementbeing provided against said body, which contact points are positionableindependently of each other in at least two independent directionsrelative to said passive part of said monolithic module, and abellow-shaped tube arranged for creating a normal force between saidmonolithic modules.
 20. Method of driving an actuator or motor havingelectromechanical material altering its shape under the influence of anelectric field, comprising the step of moving said actuator or motor byrepeating small steps, said step of moving further comprises the step ofdriving at least one monolithic module by itself or in combination withother monolithic modules, said monolithic module being a sintered blockand having electrodes integrated in said electromechanical material,positioning at least two contact points on each of said monolithicmodules independently of each other in at least two independentdirections relative to a passive part of said monolithic modules, andthe step of rotating at least one of said monolithic modules relative toanother, having a wedge shape, or relative to a separate unit having awedge shape, thereby transferring a rotating motion into a tiltingmotion.
 21. Method of driving an actuator or motor according to claim20, wherein said step of rotating comprises the steps of creation andmoving of constrictions of a central tube, causing peristaltic motion ofany liquids within said central tube.